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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2831
DTSTART:20121120T180500Z
DURATION:PT1H0M0S
DTSTAMP:20260420T021620Z
LAST-MODIFIED:20121011T182351Z
LOCATION:4274 Chamberlin (refreshments will be served)
SUMMARY:Searching for the earliest life on Earth\, Chaos & Complex Sys
 tems Seminar\, Clark Johnson\, UW Department of Geoscience
DESCRIPTION:Finding evidence for the earliest life on Earth requires a
  bit different approach than say digging for dinosaur bones\, because 
 the evidence is much more cryptic. Microbial life dominated the biosph
 ere for perhaps 4 billion years\, yet the number of known localities o
 f undisputed microfossils is quite small. What is a weird spot under t
 he microscope and what represents true cellular remains? Fossilized mi
 crobial communities (stromatolites)\, which give us a hint about ancie
 nt ecosystems\, are even more rare\, and also subject to debate. Anoth
 er approach\, one we are taking at UW-Madison\, is to look for the fin
 gerprints of ancient microbial metabolisms that are left in the isotop
 ic record of element that are cycled by life. These can be found in re
 mnant carbon compounds\, or in inorganic minerals that may be the prod
 uct of microbial metabolism. In addition\, such fingerprints inform us
  about past environmental conditions that permit\, or do not permit\, 
 life (liquid water\, etc.). We will take a broad tour of these issues\
 , focusing on what we know\, and do not know\, from the formation of t
 he Earth at 4.5 b.y. ago up to the first major rise in atmospheric oxy
 gen about 2 b.y. ago.
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URL:https://www.physics.wisc.edu/events/?id=2831
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